HPV is currently the most important papovavirus.
Seventy strains of Human Papillomavirus have been identified so far.
These viruses are known for their role in causing warts (both common
warts and genital warts) as well as their association with cancer.
Most people are infected with some strain of HPV in their lives.

This virus, found only in
humans, and is spread throughout the human population. Infection
rarely results in diseas, except in the case of the immunosuppressed.
JC virus leads to progressive
multifocal leukoencephalopathy, one
of the leading causes of death for those with HIV, and persistent
urinary tract infections. JC are the initials of the first patient
with the disease. Most people are subclinically infected with the
virus in childhood.

BK Virus

BK virus was isolated in 1971 in
a renal transplant patient. It, too, is often found in the urinary
tract of immunosuppressed individuals, but BK virus is not associated
with progressive multifocal leukoencephalopathy (PML). Infection
tends to occur early in life. Both BK virus and JC Virus are linked
to cancer.